Impedance monitoring for detecting pulmonary edema and thoracic congestion
First Claim
1. An implantable medical device comprising:
- a housing for the implantable device sized for implantation in a chest region of a patient and comprising a housing electrode;
a left ventricular lead port into which a proximal end of a lead is connectable, the lead having first and second conductors that are insulated from one another and that extend from the proximal end of the lead to corresponding first and second electrodes positioned near a distal end of the lead;
an electrical impedance measurement circuit electrically connected to the left ventricular lead port and to the housing electrode, the circuit adapted to inject current between the first lead electrode and the housing electrode, and adapted to measure a voltage potential between the second lead electrode and the housing electrode, the voltage potential created by the current injection; and
a control module adapted to calculate a series of multiple impedance value samples over a period of time, each impedance value sample being calculated based on a measurement of the voltage potential and the current injection that created the voltage potential, and to select and store in memory of the implantable device baseline impedance value samples from the series of multiple samples, wherein the baseline impedance value samples are selected based on the selected sample corresponding to a predetermined moment of both the cardiac cycle and the respiration cycle of the patient.
1 Assignment
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Accused Products
Abstract
An implantable medical device includes a housing for the implantable device that is sized for implantation in a chest region of a patient and includes a housing electrode. A left ventricular lead port is connectable to a proximal end of a lead having first and second insulated conductors that extend from the proximal end of the lead to corresponding first and second electrodes near a distal end of the lead. An electrical impedance measurement circuit is electrically connected to the left ventricular lead port and the housing electrode. The circuit may inject current between the first lead electrode and the housing electrode, and measure a voltage potential, created by the current injection, between the second lead electrode and the housing electrode. The ratio of the measured voltage to injected current may be used for assessing pulmonary edema. The lead electrodes may be located in a left ventricular coronary vein.
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Citations
28 Claims
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1. An implantable medical device comprising:
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a housing for the implantable device sized for implantation in a chest region of a patient and comprising a housing electrode; a left ventricular lead port into which a proximal end of a lead is connectable, the lead having first and second conductors that are insulated from one another and that extend from the proximal end of the lead to corresponding first and second electrodes positioned near a distal end of the lead; an electrical impedance measurement circuit electrically connected to the left ventricular lead port and to the housing electrode, the circuit adapted to inject current between the first lead electrode and the housing electrode, and adapted to measure a voltage potential between the second lead electrode and the housing electrode, the voltage potential created by the current injection; and a control module adapted to calculate a series of multiple impedance value samples over a period of time, each impedance value sample being calculated based on a measurement of the voltage potential and the current injection that created the voltage potential, and to select and store in memory of the implantable device baseline impedance value samples from the series of multiple samples, wherein the baseline impedance value samples are selected based on the selected sample corresponding to a predetermined moment of both the cardiac cycle and the respiration cycle of the patient. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A system for monitoring pulmonary edema in a human being, the system comprising:
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means for injecting an electrical current between a first electrode located in a coronary vein of a left ventricle and a housing of a medical device implanted in a chest region; means for measuring a voltage potential between a second electrode located in the coronary vein of the left ventricle and the medical device housing, the voltage potential created by the electrical current injection; and means for assessing pulmonary edema based on a baseline impedance value sample, the baseline impedance value sample selected from a series of multiple impedance values sampled over a period of time, each of the multiple impedance values being calculated based on a measurement of the voltage potential and the injected electrical current that created the voltage potential, wherein the baseline impedance value sample is selected based on the selected sample corresponding to a predetermined moment of both the cardiac cycle and the respiration cycle of the human being. - View Dependent Claims (25)
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26. A system for monitoring pulmonary edema in a human being, the system comprising:
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means for injecting a first electrical current between a first electrode located in a coronary vein of a left ventricle and a housing of a medical device implanted in a chest region; means for measuring a first voltage potential between a second electrode located in the coronary vein of the left ventricle and the medical device housing, the first voltage potential created by the first current injection; means for injecting a second electrical current between a third electrode located in a right atrium and the medical device housing; means for measuring a second voltage potential between a fourth electrode located in the right atrium and the medical device housing, the second voltage potential created by the second current injection; and means for assessing pulmonary edema based on a stored edema threshold impedance value and a baseline impedance value sample, the baseline impedance value sample selected from a series of multiple impedance values sampled over a period of time, each of the multiple impedance values being calculated based on one or more of (i) a measurement of the first voltage potential and the first injected electrical current that created the first voltage potential, and (ii) a measurement of the second voltage potential and the second injected electrical current that created the second voltage potential, wherein the baseline impedance value is selected based on the selected sample corresponding to a predetermined moment of both the cardiac cycle and the respiration cycle of the human being. - View Dependent Claims (27, 28)
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Specification